THE SEA-PEN. 185 



ened by a branching system of ribs, like the ribs and 

 fibres of a skeleton leaf. Four British species of Gor- 

 gonia, one of them common on the Devonshire coast, 

 are recorded. G. verrucosa, the commonest of these, is 

 from six to twelve inches high, and much branched, 

 like a tree ; but its branches do not form a network. 

 Its coral has a dense, black axis of a horny substance, 

 which encloses a white pith, and is coated with a whitish 

 crust, covered with warts, arranged in somewhat spiral 

 lines. Such is the aspect of the dried Polypidom. 

 When living, the crust is soft and flesh-coloured. The 

 Alcyonhim, another member of this order, has already 

 been noticed. More interesting and beautiful forms 

 are found in the family of Pennatulidce or Sea-pens, of 

 which three species, arranged under as many genera, 

 are natives of Britain. These curious animals present 

 us with the fact of compound bodies, in all respects ana- 

 logous to corals, existing in an unattached state (that is 

 not rooted or fixed to any base, but freely planted in 

 soft mud), and possibly capable of a motion through the 

 water from place to place. The fact of this motion has 

 been asserted by several naturalists, but observations are 

 wanting in corroboration. The Sea-pen itself (Penna- 

 tula phosphorea) is one of the most singular and beauti- 

 ful of the British Zoophytes. The Polypidom is three 

 or four inches in length, fleshy, of a purplish-red colour, 

 narrow and naked at the lower end, and feathered on 

 its upper half with long, closely-set pinnse, along the 

 margins of which the polype-cells are placed. These 

 pinna3 are obliquely curved backwards, and capable of 

 separate or united motion ; and they have been supposed, 



